In the past, the cross-sectional shapes of a tensioner shoe for properly retaining the tension of a transmission chain, and a shoe for guiding the running of a transmission chain or the like have substantially the same cross-sectional shape over the full length in a longitudinal direction. For example, for a roller chain, as shown in FIG. 7, the chain has pairs of outer link plates L1 and inner link plates L2 spaced apart by rollers R which pivotally interconnect the link plates, enabling flexure of the transmission chain transversely to its direction of movement to enable the chain to be trained around sprockets, pulleys and the like. The bottoms of all of the outer link plates L1, L1 and inner link plates L2, L2 (the outer link plates and the inner link plates being hereinafter generally called chain plates) of the roller chain are slidably moved in pressing contact over the full length of a shoe S in a longitudinal direction for guiding the running. For a silent chain, the chain has outer guide plates GL spaced apart by a plurality of link plates L. The link plates are pivotally interconnected to enable the chain to be trained around pulleys. In the silent chain, as shown in FIG. 8, the bottoms of the pair of guide plates GL, GL and all of the plurality of link plates L (the pair of guide plates and the plurality of link plates being hereinafter generally called chain plates) are slidably moved in pressing contact over the full length of a shoe S in a longitudinal direction for guiding the running.
Note that the shoe S for guiding the running is mounted on a shoe mounting member G such as a tensioner, a guide member or the like to retain its shape.
The chain first engages the shoe at its incoming end and disengages the shoe at its outgoing end. In the aforementioned prior art, since the bottoms of all the chain plates of the transmission chain are slidably moved in pressing contact over the full length in a longitudinal direction of the shoe for guiding the running, there poses a disadvantage in that running frictional resistance between the transmission chain and the shoe for guiding the running increases.